Process for the preparation of vinyl chloride polymers grafted on polymers of ethylene

ABSTRACT

Grafted polymers of vinyl chloride are prepared by polymerizing or copolymerizing vinyl chloride in the presence of an ethylene backbone polymer composed of polyethylene an ethylene copolymer or mixture thereof which has a fusion index &lt; OR = 250, from 0.2 to 4 double bonds per 1000 carbon atoms and/or from 5 to 30 methyl groups per 1,000 carbon atoms, under a partial pressure of vinyl chloride which is lower at all times during the polymerization than the saturated vapor pressure of vinyl chloride at the temperature of polymerization. Homogeneous products having a high degree of grafting and excellent thermal resistance and which provide in combination with polymers of vinyl chloride, compositions having improved resistance to shock, excellent transparency and processibility, are obtained by this process.

United States Patent 11 1 Dumoulin et al.

[ 51 Jan. 29, 1974 PROCESS FOR THE PREPARATION OF VINYL CHLORIDE POLYMERS GRAFTED ON POLYMERS OF ETHYLENE [75] Inventors: Joseph Dumoulin,

Wezembeek-0ppem; Marc Obsomer, Brussels, both of Belgium [30] Foreign Application Priority Data [58] Field of Search260/29.6 R, 878 R, 876, 897 C,

260/884, 29.6 CM, 29.6 RB

[56] References Cited UNITED STATES PATENTS 3,322,858 5/1967 Coaker et a1. 260/878 R 3,432,576 3/1969 Beer 260/876 R 2,947,719 8/1960 Rugg et a1 260/878 R FOREIGN PATENTS OR APPLICATIONS 652,069 8/1964 Belgium 260/878 657,762 12/1964 Belgium 260/878 Primary Examiner-Murray Tillman Assistant Examiner-J. Ziegler Attorney, Agent, or F irm-Robert E. Burns & EmmanuelJ. Lobato 57] ABSTRACT Grafted polymers of vinyl chloride are prepared by polymerizing or copolymerizing vinyl chloride in the presence of an ethylene backbone polymer composed of polyethylene an ethylene copolymer or mixture thereof which has a fusion index 250, from 0.2 to 4 double bonds per 1000 carbon atoms and/or from 5 to 30 methyl groups per 1,000 carbon atoms, under a partial pressure of vinyl chloride which is lower at all times during the polymerization than the saturated vapor pressure of vinyl chloride at the temperature of polymerization. Homogeneous products having a high degree of grafting and excellent thermal resistance and which provide in combination with polymers of vinyl chloride, compositions having improved resistance to shock, excellent transparency and processibility, are obtained by this process.

11 Claims, No Drawings PROCESS FOR THE PREPARATION OF VINYL CHLORIDE POLYMERS GRAFTED ON POLYMERS OF ETI-IYLENE BACKGROUND OF THE INVENTION The present invention relates to a process for obtaining homogeneous grafted polymers from ethylene polymers and vinyl chloride polymers which are particularly useful for applications requiring high transparency and shock resistance. The present invention also concerns mixtures of these grafted polymers with poly(vinyl chloride).

Resin mixtures with a base of poly(vinyl chloride) and polyethylene are of substantial interest in many well known fields and the combination of these two polymers has been attempted by various means. The incompatibility of poly(vinyl chloride) and polyolefins is an old problem. It is well known that the mechanical mixing of these two polymers does not yield homogeneous products and consequently, in such mixtures the desirable properties of these polymers are reduced.

Various means have been proposed to improve the compatibility of these two resins. In particular, the polymerization of vinyl chloride in the presence of polyethylene dissolved in various solvents has been disclosed in US. Pat. No. 2,947,719 of Sept. 9, 1954. However, the use of solvents decreases the grafting efficiency and alters the physical properties of the resultant products.

Accordingly procedures whereby the use of solvents are avoided have been tried, but have not resulted in a solution to the problem in view of the fact that the polymerizations have to be effected at high temperatures in the absence of solvents and the products obtained still have undesirable properties.

The polymerization of vinyl chloride in an aqueous suspension in the presence of finely divided polyethylene and in the presence of reprecipitated polyethylene has been disclosed in Belgian Pat. No. 652,069 of Aug. 20, 1964 and Belgian Pat. No. 657,762, of Dec. 30, 1964, both issued to Monsanto. However, these processes have serious drawbacks from both an economic and technological point of view. The use of finely divided polyethylene is costly; it requires the supplemental operations of reprecipitation, or the grinding or crushing of the polyethylene. On the other hand, when the polymerization is carried out in the presence of polyethylene in the solid state, e.g. in particles of relatively large size, the products obtained by means of the classical, usual processes of polymerization and particularly in aqueous suspension, have a heterogeneous structure. In addition to the fact that vinyl chloride is polymerized in the gel phase in polyethylene, it also forms homopolymeric poly(vinyl chloride) in aqueous suspension. When homopolymeric poly(vinyl chloride) forms, it is necessary to carry out the polymerization of vinyl chloride in the presence of finely divided polyethylene in order to obtain products having a homogeneous granulometry.

In addition to the above, suspension polymerization and bulk polymerization results in the formation of build up in the polymerization autoclaves which is a source of serious problems, particularly with respect to the efficiency of polymerization and contamination of the finished products.

SUMMARY OF THE INVENTION A method has now been discovered for obtaining grafted polymers of vinyl chloride and polyethylene and/or copolymers of ethylene containing a minor quantity of another olefin, whereby the problems and difficulties discussed above are avoided.

According to the present invention, grafted polymers of vinyl chloride are obtained by polymerizing or copolymerizing vinyl chloride in the presence of an ethylene trunk polymer composed of polyethylene and/or a copolymer of ethylene with a minor quantity of another olefin, in which the ethylene polymer has a fusion index equal to or less then 250, and at least one characteristic selected from 0.2 to 4 double bonds per thousand carbon atoms and 5 to 30 methyl groups per thousand carbon atoms and under a partial pressure of vinyl chloride which at all times during the polymerization or copolymerization is below that of the saturated vapor pressure of vinyl chloride at the temperature of polymerization.

By means of the present process, grafted polymers of vinyl chloride and an ethylene polymer having high proportions of grafting, composed of a single type of granules of a similar nature and composition and having a homogeneous structure, are obtained.

DESCRIPTION OF THE INVENTION According to the present process, the grafting polymerization of vinyl chloride on a backbone or trunk polymer of ethylene is carried out at a temperature of about 40 to l 10C. If the polymerization is carried out at a temperature above 110C., the grafted products as initially obtained have pronounced color due to the deterioration of the polymer.

The present process of polymerization may be carried out in aqueous suspension or in bulk in the absence of water.

The vinyl chloride/trunk polymer ratio in the polymerization medium is not critical, providing that the partial pressure of vinyl chloride in the polymerization autoclave is at all times below that of the saturated vapor pressure of the vinyl chloride at the temperature of polymerization. In accordance with the present invention, the polymerization is carried out so that the vinyl chloride introduced into the polymerization mixture is almost completely absorbed by the trunk polymer and hence is polymerized in direct contact therewith. Accordingly, the vinyl chloride/trunk polymer ratio depends on the nature of the trunk polymer and more particularly on its capacity for absorbing vinyl chloride.

By carrying out the polymerization in this manner, the grafting efiiciency is improved and the formation of homopolymeric vinyl chloride outside the particles of g the trunk polymer is avoided. The grafting efficiency is defined by the following relationship: [g. of grafted trunk polymer/ g. of polymerized poly(vinyl chloride)]X The process of the present invention is in essence distinguished from prior processes due to the fact that in the known processes, the vinyl chloride/trunk polymer ratio is greater than that corresponding to that of the saturation of the grains of trunk polymer and, consequently, heterogeneous products are obtained because the non-absorbed vinyl chloride forms homopolymeric poly(vinyl chloride) outside of the grains of the polymer trunk. Moreover, the formation of homopolymeric poly(vinyl chloride) considerably reduces the grafting efficiency.

In the process of the invention substantially all of th vinyl chloride introduced into the polymerization reaction is polymerized in direct contact with the polyethylene trunk polymer, which thereby results in an increase in the grafting efficiency.

It has also been found that during the course of polymerization, the particles of polyethylene are capable of rapidly absorbing additional quantities of vinyl chloride. Thus, by continuously or discontinuously introducing supplemental quantities of vinyl chloride during the polymerization, and optionally a catalyst, quantities of vinyl chloride greater than those which correspond to the initial saturation of the polyethylene trunk polymer by vinyl chloride may be polymerized in contact with or inside the particles of polyethylene. However, the supplemental additions of vinyl chloride are such that the partial pressure of vinyl chloride in the polymerization reactor is always to be maintained at a pressure which is below the saturated vapor pressure of vinyl chloride at the temperature of polymerization. By carrying out the operation in this manner, the proportion of grafting of the polymer trunk, i.e. on the backbone polymer, is increased.

The grafting efficiency and the proportion of grafting are also increased when the ratio ofvinyl chloride/- polymer trunk is reduced. Thus, such techniques, i.e. the introduction of supplemental quantities of vinyl chloride during the polymerization, are particularly interesting when trunk polymers are used which have a relatively low absorption capacity for vinyl chloride.

The quantity of vinyl chloride which may be absorbed by the backbone polymer depends on the nature of the backbone polymer, To determine the maximum quantity that may be used, vinyl chloride in an aqueous suspension of polyethylene is continuously introduced. At the same time the pressure increases continuously and the maximum quantity absorbed is reached when the pressure stops increasing.

All polyethylenes and ethylene copolymers containing 0.4 to 6 mole percent of an alpha olefin such as propene, butene and hexene, capable of being swelled by vinyl chloride at a temperature of 40 to 110 C and which meet the following requirements, can be used in accordance with the process of the present invention:

A fusion index (ASTM D 123857 T) equal to or lower than 250 and preferably between 0.1 and 200.

The number of double bonds per 100 carbon atoms is from 0.2 to 4, determined by infra-red spectrophotometry, and/or The number of methyl groups per 1,000 carbon atoms is from to 30, as determined by infra-red spec- Pat. No. 1,466,376 of Apr. 11, 1965, issued to Solvay & Cie, S.A., are also suitable for carrying out the invention. The foregoing patent, as well as other publications mentioned herein are incorporated by reference.

The products obtained in accordance with the present invention may contain almost any quantity of grafted polymer. However, the products of the present invention generallly contain from about 25 to percent of grafted polymer, the balance being composed of non-grafted polyvinyl chloride and unmodified polyethylene when the initial trunk polymer is in granular or powder form. Non-grafted poly(vinyl chloride) and unmodified polyethylene are generally found in proportions of about 40 to 60 percent of the total of the non-grafted products.

The present process is particularly interesting for preparing resins wherein the total quantity of ethylene, which may be modified or not, is about 25 to 99 percent by weight of the final product and more particularly, from about 30 to 70 percent by weight when the initial polyethylene trunk polymer is in granular form, i.e. powder, fluff, granules and the like, and from to 99 percent by weight when the grafting of vinyl chloride is carried out on finished polyethylene objects such as fibers, films, plates, etc.

The incorporation of the grafted products obtained in accordance with the present invention and in particular mixtures thereof with poly(vinyl chloride) have substantially improved resistance to shock. The transparency and resistance to shock of mixtures containing grafted resins of the present invention are clearly higher than those of corresponding mixtures which do not contain a grafted polymer but which contain an equivalent proportion of the trunk polymer. Compositions containing from 1 to 25 parts and more preferably from 5 to 20 parts of the grafted product of the present invention per 100 parts of poly(vinyl chloride) are par ticularly useful.

By employing ethylene trunk polymers having a fusion index of about 0.3 to 40, grafted polymers having a highly desirable proportion of grafting are obtained, for example about 40 percent to about 60 percent.

When a trunk polymer having a fusion index equal to or lower than 0.3 is used, a further increase in the proportion of grafting may be obtained and consequently, the quantity of unmodified ethylene polymer in the grafted products may be reduced. Thus, polymers of ethylene having a fusion index between about 0.1 and 0.3 are particularly suitable for obtaining resins having a high proportion of grafting.

Polymers having a fusion index lower than about 0.05 and in some cases lower than 0.1 are not often suitable for use in the present process in view of the fact that they are not especially capable of absorbing a sufficient quantity of monomer so as to expand under the conditions of polymerization or of reacting under the grafting conditions.

By carrying out the grafting operation in accordance with the invention, the compatibility of compositions which contain such grafted resins and poly(vinyl chloride) is increased, whereby compositions of excellent transparency are obtained. Also as a result of the improvement of compatibility a very high quantity of grafted polymers may be incorporated with poly(vinyl chloride) whereby compositions having still further improved resistance to shock and at the same time excellent transparency are obtained.

By using an ethylene polymer having a fusion index equal to or greater than 40 and equal to or lower than 250 and, preferably, between about 40 and 200, as the trunk polymer, grafted polymers may be obtained which when combined with poly(vinyl chloride) provide compositions having greatly reduced viscosity in melted form. Compositions of this type may be worked at relatively low temperatures. Moreover, these compositions have excellent thermal stability and a good initial coloration. In addition, when working with such compositions, due to the reduced viscosity, the productivity may be increased without risk of deterioration of the polymer. These compositions also have good transparency and resistance to shock.

Ethylene polymers which have a fusion index greater than 250 are generally not suitable for the purposes of the present invention in view of the fact that combinations thereof with poly (vinyl chloride) only very slightly improve the mechanical properties and particularly the resistance to shock of the vinyl chloride polymer.

Polymers of ethylene in almost any form may be used in the process of the present invention, and in particular, the polyethylene may be in the form of powder, granules, fluff, fibers, plates, films, other finished objects and the like. Preferably the ethylene trunk polymer is employed in the form of fluff or gelled granules having an average granulometry of about 1 to mm. and preferably of 3 to 8 mm. The proportion of ethylene trunk polymer and vinyl chloride used in the process varies according to the type of grafted polymer desired as well as the absorption capability of the polyethylene.

Catalysts and catalytic systems which generate free radicals and are soluble in vinyl chloride which are in general use for the polymerization of vinyl chloride may be used in the present process. The quantity of catalyst is preferably about 0.01 to 5 percent by weight based on the amount of monomer in the reaction. The catalysts may be introduced into the reaction mixture in solid form, in a solution of the vinyl chloride or solvent used to expand the polyethylene. The process of the present invention may be carried out in the presence of water as the liquid dispersion medium or without water.

When the grafting operation is carried out in the presence of water, it is preferable to incorporate in the reaction, the additives usually employed in the art of aqueous suspension polymerization. As suspension agents, materials which have a good wetting effect with respect to the trunk polymer are used including macromolecular colloids, ionic and non-ionic surface active agents. By carrying out the grafting process in accordance with the present invention, the formation of poly(vinyl chloride) in aqueous suspension may be avoided.

Agitation of the reaction medium does not have any effect on the characteristics of the polymer particles which are formed; it influences only the kinetics of absorption of the vinyl chloride by the trunk polymer. The reaction medium is therefore subject to continuous agitation by means of effective agitators driven at appropriate speeds.

In accordance with a particular embodiment of the present process, the grafting polymerization reaction may be carried out in the absence of water by employing a suitable apparatus which provides good agitation of the reaction medium, particularly an apparatus such as a vertical autoclave with strap agitators, a fluid bed reactor and the like. Products obtained by means of this technique do not require washing or drying and have a high degree of purity due to the absence of dispersion agents which contaminate the polymers during polymerization.

Any known suspension agent may be used. Suitable suspension agents are disclosed in H. KAINER Polyvinylchlorid und Vinylchlorid Mischpolymerisate Springer Verlag 1965 p. 12-34.

Resins having improved stabilization may also be obtained by means of the present process by incorporating in the reaction medium, either before or during the polymerization reaction, one or more of the usual stabilizers of poly(vinyl chloride). This procedure assures that the stabilizer is well dispersed in the resin and thereby provides a high stabilizing efficiency of the stabilizing agent.

The present process may also be used for the copolymerization of vinyl chloride with other polymerizable monomers such as vinylidene chloride, ethylene, propylene and the like. The maximum quantity of comonomer is 30 percent by weight. Suitable comonomers are vinyl esters such as vinyl acetate; acrylic and methacrylic esters such as alkyl acrylates and methacrylates; vinylidene halogenides such as vinylidene chloride; alpha olefins such as ethylene, propene, butene and hexene.

Grafted polymers including the above-mentioned grafted copolymers obtained in accordance with the present process have a high proportion of grafting. When such products are incorporated with other resins and particularly with vinyl chloride polymers, the compositions have substantially improved resistance to shock. The transparency and resistance to shock of the mixtures containing the presently grafted polymers are clearly greater than those of corresponding mixtures containing an equal proportion of the trunk polymer, but which do not contain a grafted trunk polymer, prepared in accordance with the present invention.

By polymers of vinyl chloride, which when mixed with the presently grafted polymers provide compositions having especially desirable characteristics, it meant homopolymers of vinyl chloride and copolymers of vinyl chloride containing less than 50 percent of a copolymerizable monomer and also postchlorinated polymers particularly postchlorinated poly(vinyl chloride) which contains from about 600 to 750 grams of chlorine per kilogram.

Moreover, by incorporating the present grafted product in compositions with other resins such as poly(vinyl chloride), the use of processing-aids and reinforcing agents which are well known in the art and which are commonly employed at the present time may be eliminated, i.e. components such as the methylmethacrylate ethylacrylate copolymers of ethyl and methyl acrylates (PARALOID K l2ON) finely, divided low density polyethylenes (MICROTHENES FN 500 and MN 1710) as well as the grafted polymers obtained by grafting monomers such as methyl methacrylate, styrene, acrylonitrile, etc. on a polymer of butadiene (KUREHA BTA III).

Compositions based on poly(vinyl chloride) having a high molecular weight and also containing the grafted polymers of the present invention may be easily transformed into bottles or other forms without deterioration of the excellent properties of the composition mentioned above. In addition, the usual addition of a reinforcing agent customarily utilized may be eliminated, which has not been possible up to the present tomarily required. Accordingly, the characteristics of such compositions make it possible to obtain finished products having excellent thermal stability and good initial color. Compositions containing the present time, in view of the fact that the polymer has been degrafted product also retain the properties of good transgraded when it is processed. By poly(vinyl chloride) parency and resistance to shock mentioned above. having a high molecular weight is meant the polymers By means of this technique, grafted products having which have a Fikentscher K number measured in 1,2- a granulometry lower than 1 mm. may be obtained dichloroethane above 57 and more specifically of 58 to starting with a backbone polymer having a granulome- 67. try of from 2 to 10 mm. and preferably from 3 to 4 mm.

On the other hand, compositions composed of the The granulometry of the particles is determined by presently grafted polymers and poly(vinyl chloride) sieving with calibrated sieves. By selecting suitable ophaving a low molecular weight, i.e., a K number below erating conditions, and in particular the type of back- 57 and more specifically of 52 to 55, allow a higher bone p y the nyl ri e/b ckbone polymer, productivity of industrial molding machines. the fineness of the grains of the grafted product may be It is also particularly useful to obtain grafted products regulated, and in Particular, Products With a g in finely divided form; in view of the fact that in such lometry of between 50 and L F and Preferably form, the incorporation of customary additives and the the Order Of y be Obtained For Operating use of premixes is facilitated. peratures of about 90 to 100 C. and for the backbone when the grafting polymerization procedure dispolymers CR Shown in Table i, it is desirable to operclosed herein is carried out at a temperature of about ate With a ratiO of inyl de/ ckbone polymer re- 80 to 110C, finely divided grafted products may be p i y 0f -5 I0 obtained directly without supplemental separation By means of the process of the present invention, hooperations starting with polyethylene in granular form. mogeneous grafted polymers are obtained, the cffi- It is indeed surprising in the light of the results of stan- Ciency of grafting is improved and in addition, the prodard processes for polymerizing vinyl chloride in $115. cess is economical due to the absence of build-up in the pension, in emulsion, or in bulk or mass, that the prespolymerization reactor. Moreover, the proportion of ent process of graft polymerization may be carried out effective filling of resin in the polymerization reactor at temperatures of about 80 to l 10C. to provide unincreases with the granulometry of the backbone polycolored grafted products having a high proportion of mer mployed. grafting and good thermal stability. Moreover, the The characteristics of the grafted polymers cited grafted polymers obtained according to the present above yield materials of choice for numerous applicaprocess improve the fluidity of mixtures in melted form tions in particular, for the production of corrugated or which contain polymers of vinyl chloride. Conse- 5 flat plates, sheets, containers, and the like.

quently, these compositions may be processed with The polymers of ethylene used in the examples degreater facility at lower temperatures than those cusscribed hereinafter are set forth in Table 1.

TABLE 1 Characteristics of Polyethylene Polymers No. of double Number of methyl Des- Polymer Trunk Index of Specific Weight bonds p g p p ig- Fusion (g./cm.-") 1000 C 1000 C na- (g./l0 min.) ASTM D 1505-57 T Granulotion Nature Form ASTM D l238- metry Measured by infra-red 57 T (mm.) spectrophotometry Polyethylene Microspheres 22 0.915 0.02 0.6l 16 low density obtained by A reprecipitation Polyethylene Powder Ob- 22 0.9[6 0.3 0.73 17 low density tained by grinding Polyethylene Granules 21 0.919 4.7 0.64 16 low density extruded Ethylene] Fluff 2.2 0.926 2.5 0.21 l5 butene copolymer E Ethylene/ Fluff 30 0.955 2 0.20 5

butene copolymer Polyethylene Fluff 3.7 0.96 2 L 0 high density G Polyethylene Fluff 0.25 0.958 l 0.17 1

high density Powder obtained by 0.914 0.3 0.59 l8 L Polyethylene grinding 200 0.913 0.3 0.60 20 M low 0.25 0.925 3 to 4 0.4 12 N density 0.29 0.922 3 to 4 0.45 l3 0 Granules 2 0.9l8 3 to 4 0.57 14 P extruded 7 0.917 3 to 4 0.49 17 R 70 0.914 3 to 4 0.59 18 EXAMPLES 1 to 6 In an autoclave of 1., subjected to a continuous agitation (450 revolutions per minute), with the aid of a The non-grafted trunk polymer is extracted with cyclohexane when the trunk polymer is completely soluble in this solvent; when the trunk polymer is insoluble in cyclohexane, separation is effected by means of gel chromatography.

The proportion of grafting is then calculated in accordance with the following formula, 1 A-B/A X 100, in which A is the total weight of the trunk polymer in the sample and B is the weight of the non-grafted trunk polymer.

The characteristics of the polyethylenes employed as the polymer trunk are given in Table l; and those of the grafted products obtained are set forth in Table 2.

TABLE 2 Granulometry, g./kg.

Size of the Poly- Polymers obtained Poly- Polymers obtained Poly- Polymers obtained in Particles ethylene in examples ethylin examples ethylene examples mm. A 1 R2 ene B R4 C 0.043 I000 186 97 0.089 566 131 0. I 693 15] O.l75 778 I93 0.246 813 246 0.295 827 300 I000 916 849 O.35l 837 36] 988 985 O.4l7 845 444 992 99] ().495 852 537 995 993 0.589 859 620 999 995 O.7l() 863 695 l()()() 996 0.833 867 745 997 l 872 810 999 l.397 899 914 1000 I .981 955 985 2.794 998 998 8 2 2 3.327 999 999 115 5 6 4.699 1000 I000 I000 995 996 6.73 I000 1000 Table 3 Examples 1 R2 3 R4 5 6 Constituents.

parts by weight Vinyl chloride 500 Polyethylene A 500 B 500 C 500 Water 1750 Poly(vinyl alcohol) 9 0.9 0.9 0.45 0.9 0.18 Lauroyl peroxide 1.5 Temperature of polymerization, C. 68 Period of reaction, hours 4 6.25 5 3 3.5 3 Yield of the polymerization, 7O 75 92,5 88 9O 86 Proportion of grafting of PE,

two-blade agitator inclined at 45, the following is introduced: water, suspension agent and polyethylene in the proportions set forth in Table III. After the introduction of the catalyst, the vinyl chloride is introduced in such a quantity that at the temperature of polymerization (68C.), the partial pressure of the vinyl chloride is lower than the saturated vapor pressure of vinyl chloride at 68C.. namely, 11.6 kg./cm. When the pressure has dropped to at least half its maximum j value, the non-transformed gaseous vinyl chloride is re- The examples preceded by the letter R are comparative examples in which the pressure reaches the saturated vapor pressure of the vinyl chloride during at least a part of the polymerization.

In connection with Examples 1, 3, 5 and 6, it has been found that contrary to the classical procedures of polymerizing vinyl chloride in aqueous suspension, the pressure at the start of the polymerization reaction is not level; instead the pressure drops immediately as soon as the reaction temperature is reached. This phenomenon clearly indicates that the vinyl chloride has been substantially absorbed by the backbone polymer; no vinyl chloride polymerizes in aqueous suspension outside of the polyethylene granules.

Thus, the amount of suspension agent was sufficient for permitting a correct dispersion of the backbone polymer in the liquid phase and for ensuring a fast absorption of vinyl chloride by polyethylene. The amount of suspension agent is different according to the granulometry of the backbone polymer used.

In connection with the comparative examples R2 and R4, the level of partial pressure of vinyl chloride in the autoclave was equal to the saturated vapor pressure of vinyl chloride at 68C. for a period of more than two hours (Example R2) and over a period of more than 30 minutes (Example R4).

The amount of poly(vinyl alcohol) was insufficient for correctly dispersing the polyethylene in the liquid phase. Consequently, the absorption of vinyl chloride is too slow and homopolymerization of vinyl chloride already occurs in aqueous suspension outside of the polyethylene granules.

The average granulometry of the products which were obtained in accordance with Examples R2 and R4 is higher than that of the products obtained in Examples l and 3, respectively, which indicates the presence of agglomerates.

The process according to the present invention makes it possible to reduce considerably the amount of suspension agent required to assure good dispersion of the backbone polymer and a rapid absorption, of the vinyl chloride when the backbone polymer is in the form of granules, as shown in Examples 5 and 6.

EXAMPLE 7 Polymerization is carried out according to the same technique described in Examples 1 to 6 and in the presence of the components of Example 5, but by adding supplemental quantities of vinyl chloride during the course of polymerization.

As soon as the pressure in the autoclave has dropped to 9.5 kg./cm. an additional 50 cc. (33 parts) of vinyl chloride are introduced. The same operation is repeated fifteen times as soon as the pressure has reached 9.5 kg./cm. All together, 500 supplemental parts of vinyl chloride are added.

After five hours of polymerization, the yield of polymerization is above 94% and the proportion of grafting is 60 percent. It is evident that the proportion of grafting the polymer has been improved by increasing the quantity of vinyl chloride introduced by adding successive fractions of vinyl chloride during the course of polymerization.

EXAMPLE 8 This example demonstrates that the efficiency of grafting and the proportion of grafting of the polymer trunk are improved by reducing the ratio of vinyl chloride/polyethylene existing in the reaction medium during the course of polymerization, and at the same time maintaining the conditions in accordance with the present invention.

In'an autoclave of 5 1., equipped with an agitator having blades inclined at 45, rotating at 450 revolutions per minute, 0.9 parts by weight of poly(vinyl alcohol) are introduced as well as 1,750 parts of water, and then 500 parts of polyethylene B are dispersed in the mixture. Forty percent of a solution of 1.5 parts of lauroyl peroxide are added in 7.5 parts of benzene and 200 parts of vinyl chloride. The reacting medium is then brought to a temperature of 68C. The prevailing pressure in the autoclave is 8.7 kg./cm.

After 105 minutes of reaction, an additional 15% of the catalyst solution and parts of vinyl chloride are introduced into the reaction mixture. The operation is repeated after another period of 105 minutes and this is done four times.

After 11 hours of reaction, a polymer is obtained in which the proportion of grafting is 56 percent.

The yield of the reaction is above percent.

EXAMPLE R9 In a 30 l. autoclave, equipped with a two-blade agitator inclined at 45, there is introduced 0.9 parts by weight of poly(vinyl alcohol), 1750 parts of water and 550 parts of polyethylene B is dispersed in the mixture.

The product obtained contains agglomerates of polyi ethylene grafted with granules of poly(vinyl chloride) connected to each other by homopolymeric poly(vinyl chloride) which has been polymerized outside of the polyethylene grains. The characteristics of the product thus obtained clearly demonstrates the influence on the granulometry of the grafted product as well as on the polymer itself which is to be grafted of the presence of an excess of vinyl chloride as compared to the saturation of the grains of polyethylene in accordance with the present process.

On the other hand, the presence of a level pressure during the polymerization clearly indicates that the pressure prevailing in the autoclave at the beginning of the reaction was equal to the pressure of the saturated vapor of the vinyl chloride at 52C., which explains the formation of poly(vinyl chloride) outside of the grains of polyethylene.

EXAMPLE 10 This example illustrates the grafting copolymerization of vinyl chloride and vinylidene chloride in the presence of polyethylene.

In an autoclave of 16 1., equipped with a three-blade agitator rotating at a speed of 275 revolutions per minute, the following is introduced: Nine tenths parts by weight of poly(vinyl alcohol), 1750 parts of water and 500 parts of polyethylene B are dispersed in the mixture. There is then added 1.5 parts of lauroyl peroxide and 333 parts of vinyl chloride (1660 grams) as well as 50 parts of vinylidene chloride. The autoclave is then brought to a temperature of 68C. The prevailing pressure in the autoclave is 9 kg./cm.

There is then introduced every hour, 16.7 parts of vinylidene chloride; the total number of such introductions is 7.

After 4 hours of reaction, 1.5 parts of lauroyl peroxide are added.

The polymerization reaction is stopped after a period of 8% hours of reaction and a grafted polymer is obtained having a proportion of grafting of 38% and the yield of polymerization is over 93 percent.

13 14 EXAMPLES l I TO R14 grafted trunk with cyclohcxane, and are given in Table The polymerization of vinyl chloride is carried out in the presence of different trunk polymers, namely, the Table 5 polymers of ethylene designated D, E, F and G, the characteristics of which have been described in Table 5 Examples l5 6 17 l l Polyethylene 0 p C The polymerization technique employed is the same Proportion of grafting, 67 60 55 as that of Examples 1 to 6, but only part of the vinyl chloride is introduced at the beginning of the reaction, the rest being added in successive fractions during the The degree of grafting is then calculated in accorcourse of polymerization, so that the pressure of the dance with the following formula t= (A-B/A) X 100,

vinyl chloride vapor always remains lower than its satuin which A is the total weight A of the backbone polyrated vapor pressure at the temperature of polymerizamer in the sample and B is the weight of the noni grafted backbone polymer.

The various components introduced in the autoclave The high degree of grafting obtained is clearly evias well as their proportions are set forth in Table 4. dent.

Table 4 Constituents, Examples ll l2 13 R14 parts by weight Vinyl chloride 500 Polymer of Ethylene D 500 E 500 F 500 o 500 Water 1750 Poly(vinyl alcohol) 36 Lauroyl peroxide 1.5 Temperature of reaction, C. 68 Period of reaction, hours 3.5 4.5 8 8 Yield of polymerization, 87 90 90 80 Proportion of grafting 40 33 60 l5 Example R14 shows clearly that with a polymer of EXAMPLE l8 .ethylene which does not meet the features or charac- The p 01y merization of vinyl chloride is Carried out in teristics which are required according to the present the presence of polyethylene B and in the absence f invention, the proportion of grafting the resultant polywater and a Suspension agent 15 y In an autoclave of l 1., there is introduced 500 parts EXAMPLES 5 o 17 of polyethylene B, 2 parts of lauroyl peroxide and vinyl Th 1 f 1 h] d chloride in a quantity such that at the temperature of 6 p0 ymenzauono C on e 18 came 0mm polymerization of 62C., the partial pressure of the g a of differeni tiunk polyfngrs designgted 9 vinyl chloride prevailing in the autoclave is lower than an t e charactensilcs of whlc Set m the saturated vapor pressure of the vinyl chloride at Table 1 In accordance with the following polymerrza- No liquid phase is observed in the polymeriza non technique: tion reactor and the reacting mixture acts like a dry an {wtqclave of q p a two'blade free-flowing powder. As soon as the reaction starts, mchned at 45 there IS mtfoduced 9 parts a drop in pressure is observed which is compensated by by welght of water parts y weight of poly(vmyl the successive introductions of vinyl chloride regulated c9hol) 1000 arts by welght of polyethylene are in such a manner as to maintain the pressure at about dispersed in the mixture. There is then added 3 parts by 8 kgJcmg' After Seven hours of reaction the Oflaumyl pfmide and 5 parts by weight of transformed vinyl chloride is degassed and a freeoxidrzedsoybean oil. flowing powder is collected which does not require There 15 then introduced 600 parts by weight of vinyl centrifugal drying or regular drying chloride. This quantity is such that at the temperature The polymer Obtained has a degree of grafting of 44 of polymerization (62C) the partial Pressure of the percent. Moreover, no build-up is observed in the reacvinyl chloride prevailing in the autoclave is lower than the saturated vapor pressure of the vinyl chloride,

namely, 10.2 kg/cmf'z As soon as the temperature of EXAMPLE l9 reaction is reached, the pressure drops and is brought The polymerization of vinyl chloride is carried out in back to its initial point by four successive additions of an autoclave of 5 l., in the presence of plates having a 100 parts by weight of vinyl chloride. After six hours of thickness of from 1.5 and 3 mm., of the ethylene polyreaction, the pressure drops to below 6 kg./cm. mer C, prestabilized with the aid of 1 percent di- The non-polymerized vinyl chloride is then degassed phenyldecyl phosphite and arranged in star formation and a product is collected and the proportion of graftaround the axis of the agitator.

ing is determined. The yield of the polymerization is ap- After having added a quantity of a solution of poly(- proximately 90 percent, and no crusting is observed on vinyl alcohol) in water (0.1 g./kg. of water) to the exthe walls of the reactor. The proportion of grafting (r) tent that the polyethylene plates are immersed, lauroyl of the products is determined by extraction of the nonperoxide (2 g./kg. of vinyl chloride) is introduced and the vinyl chloride is added in such a manner that the prevailing pressure in the autoclave at the temperature of polymerization (62C.) is equal to 6 kg./cm.

The pressure is maintained between 6 and 8 kg./cm. during the course of the reaction by means of the successive introductions of vinyl chloride.

After six hours of reaction, the non-transformed vinyl chloride is degassed and plates are collected containing 100 grams of partially grafted poly(vinyl chloride) per kg. of the product.

EXAMPLE The polymerization of vinyl chloride is carried out in the presence of polyethylene by reducing the ratio of water/vinyl chloride plus polymer trunk and by adding a stabilizer to the polymerization medium. By carrying out the operation in this manner, the productivity of the autoclave is increased and the costs of drying the final product as well as the amount of suspension agent employed are reduced.

In an autoclave of 30 l., equipped with a two-blade agitator inclined at 45, 750 parts of water, 0.4 parts of poly(vinyl alcohol) and 500 parts of polyethylene C are dispersed. After having added 1.5 parts of lauroyl peroxide and 2.5 parts of epoxidized soybean oil as a stabilizer, 300 parts of vinyl chloride (7440 grams) are introduced. The autoclave is then heated at 62C. and the pressure prevailing therein is 9.5 kg./cm. From the start of the reaction the pressure drops, and it is then brought to its initial limit by four successive additions of 50 parts of vinyl chloride.

After six hours of reaction, a product is obtained having a proportion of grafting of 45 percent. The yield of the polymerization is 93 percent.

EXAMPLES 21 TO 43 Mixtures with a base of grafted polymers which are obtained in accordance with the foregoing examples are incorporated into poly(vinyl chloride) obtained by means of polymerization in suspension and having a number K measured in cyclohexanone solution equal to 7l in such a manner that the content in polyolefm in the mixture is equal to 7.5 percent, that is, 15 percent by weight of the product having a grafted polymer base.

As a matter of comparison, mixtures of PVC containing 7.5 percent of non-grafted trunk polymers are also prepared (Examples R21 to R28).

After malaxation on a cylinder malaxator during a period of five minutes at 180C. in the presence of standard ingredients, a crepe is obtained which is transformed into plates by pressing at 190C. for a period of five minutes.

The following properties are then measured on these plates:

IZOD resistance to shock at room temperature of 20C., in accordance with the ASTM D 256/56 Standards;

light transmission on plates having a thickness of 2 mm. in accordance with the ASTM 1003/61 Standards.

The results of these tests are indicated in Table 6 and clearly demonstrate that the grafted polymers according to the invention increase the resistance to shock of the compounds having a base of poly(vinyl chloride) and that the latter have a transparency and a resistance to shock which is improved as compared with nongrafted mixtures.

The incorporation of the polymer obtained in Example R14 with poly(vinyl chloride) wherein the trunk polymer which does not meet the requirements of the present invention does not have a favorable effect on the resistance to shock and the transparency of the grafted composition, as compared to the non-grafted composition.

TABLE 6 Composition Light Transmission lZOD Resistance to Shock according to Examples of the according to ASTM 1003/61 ASTM D 256/56 kg.cm./cm.

Mixture of Transmission Haze R21 Polyfvinyl chloride) 84 16 3.5

R23 poly(vinyl B 42 100 8 R24 T c 39 100 9 7.5% of R25 p ly lefin D 59 100 6.5 R26 E 92 5 R27 F 62 100 45 R28 0 73 3.5

29 l 47 98 l4 3O 2 47 I0 3] 3 5l )3 I4 32 4 49 92 l 15 Poly( vinyl 33 chloride) 5 49 89 I2 34 6 53 86 I6 35 Product 7 57 7O 15 36 obtained in 8 59 79 14 the examples 37 9 53 9l 8 38 1O 37 91 6.5 39 ll 63 92 8.5 4O 12 74 51 6 4] I3 77 35 6.5 '42 I4 70 88 15 43 I8 56 87 ll 20 59 83 16 17 EXAMPLES 44 AND 45 ln these examples, the technique of polymerization is the same as that of Examples 15 and 17.

The yield of the polymerization is approximately 90 vinyl chloride) and assure an improved transparency.

With equal transparency, these products can have a higher proportion of poly(vinyl chloride) and conseinvention increase the resistance to shock of the poly(- percent and no build-up is observed on the walls of the quently the result is products having an even higher rereactor. sistance to shock.

The proportions of grafting ('r) of the products are in addition thereto, the products according to the indetermined by means of the extraction of the nonvention have a transparency and a resistance to shock grafted trunk of cyclohexane. The proportions of graftgreatly improved as compared to the non-grafted mixing are given in Table 7. tures.

TABLE 8 Examples Composition of Mixture Ptroportion Light Transmission 1200 Resistance to Q It f 1- d t Shk dr 3325 23am 3153i" xffiil' 53731 A"sT-?55Z/%6 Nature in the mixture, the mixture of kg.cm./cm.

% by weight by weight transmission haze Poly(vinyl chloride) plus product obtained in example 46 45 7.5 66 72 15 47 45 10 60 so 19 R48 Poly(vinyl chloride) 7.5% of polyethylene Table 7 EXAMPLES 49 AND 50 The technique of polymerization employed is the fol- Examples 44 45 lowing: polyethylene M N In an autoclave of 30 liters, equipped with a twofPP of 85 80 blade agitator inclined at 45, 3,200 parts by weight of gm water, 1.8 parts by weight of poly(vinyl alcohol) and 1000 parts of polyethylene are introduced and disa d. Lauro l eroxide in an amount of 4.2 arts b The high proportion of grafting when using polyethpetse y p p y ylenes having a fusion index below 0.3 is evident. The we'ght h There, mtrodllcefd 600 degree of grafting is calculated as described above. parts by welght of Vmyl chloride Thls ,quantty Such that at the temperature of polymerization (62C.), the EXAMPLES 46 TO 48 partial pressure of the vinyl chloride prevailing in the The grafted polymer Obtained in accordance with autoclave is lower than the saturated vapor pressure of t 40 the vinyl chloride, namely, 10.2 kg./cm. ample IS incorporated into poly(vmyl chloride) ob- A h f 62C tained by Polymerization in suspension and having a K 8 Soon as t temperature? reaction l' number measured in 1,2-dichlorethane solution equal h pressure drops and 1S brought back to us to 66 so that the content in polyolefin in the mixture tial limit by means of four successive additions of 100 is equal to 7.5 percent (Example 46) and 10 percent 45 parts by weight of vinyl chloride. After six hOlfS of re- (Example 47) respectively, that is, 15 and 20 percent action the pressure. drop? to 6 P by weight of the product is graft e d p 01y m e r. The non-polymerized vinyl chloride is then degassed As a matter of comparison, a mixture of poly(vinyl f f product.ls collected and he proportlon of graftchloride) is prepared containing 7.5 percent by weight mg i 5 by f fg p g f of the polymer of non-grafted ethylene N (Example l wlt p exam 8 yle o t e y i R48) tron is approximately 90 percent and no crustmg is ob- After malaxation on a cylinder malaxor for a period g fi on i s i i i T bl of 5 minutes at 180C. in the presence of standard in- 6 Prop r o S 0 gm mg are gwen m a e .gredients, a crepe is obtained which is transformed into Table 9 plates by pressing at 190C. for a period of 5 minutes.

Examples 49 50 The following properties are then measured on these P l h l K L plates: resistance to shock IZOD at the room temperaf fjj l j fi ture of 20C. in accordance with the ASTM D 256/56 grafting 47 50 Standards. 60

llght transmission 9 Plates having a thlckness of 2 The degree of grafting is calculated as described mm. in accordance with the ASTM 1003/61 Standards. above The results of these tests are indicated in Table 8. and EXAMPLES 51 To 53 demonstrate that the grafted polymers according to the 65 The products obtained in accordance with Examples 49 and 50 hereinabove are incorporated into poly(vinyl chloride) obtained by polymerization in suspension and having a K number measured in 1,2-dichloroethane equal to 66, in such a manner that the content of polyolefin in the mixture is equal to 7.5 percent, i.e. the mixture contains 15 percent by weight of the grafted product.

After malaxation on a cylinder malaxator for a period of five minutes at 180C. in the presence of standard ingredients, a crepe is obtained which is cut into fine strips and the apparent viscosity is determined in a Gottfert and Wiedmann viscosimeter.

The results of these tests are set forth in Table 10 and demonstrate that the grafted polymers of the invention improve the fluidity of compositions which have a base of poly(vinyl chloride) and thereby the working of these compounds is greatly facilitated.

Table l I chloride) containing no additive for improving injectability.

Comparative Example R60 pertains to a mixture of poly(vinyl chloride) and a coumarone-indene resin noted for its fluidifying properties.

Gottfert & Wiedmann Examples Composition of the Mixtures Viscosity at l80C. and

at I00 see R51 Poly(vinyl chloride) at 52 Polyvinyl chloride 49 4.1

53 Products obtained in examples 50 3.2

The results of the tests are set forth in Table l l and clearly demonstrate that the injectability has been improved by by means of the present grafted products compared with that of poly(vinyl chloride) without an additive, and an injectability capacity is reached which is equivalent to that of a compound containing a coumarone-indene resin. In addition, the excellent properties of resistance to shock (ASTM D 256/56 Test on injected bars) are retained.

Table 11 Examples R54 R55 56 57 Composition, g. Poly(vinyl chloride) K number 53 100 94 87 87 Products obtained in examples 49 l3 5O l3 Coumarone-indene resin 6 Lead stabilizer 4.4 4.4 4.4 4.4 Epoxidized soybean oil 4 4 4 4 Properties Length of the spiral cm. l9 27 26 27 IZOD resistance to shock (20C.) according to ASTM D 256/56,kg.cm./cm.of 2.8 2.5 4.3 4.1

notch Appearance of injected objects Beautiful Starting with the compounds indicated hereinbelow, the spiral injection test is carried out to determine the injectability of the compounds by measuring the length of injected spirals.

This test consists of injecting on an injection press of the Ankerwerk type an object the form of which is a spiral with an unspecified length. This spiral is formed by a band 20 mm. wide by 1.6 mm. thick wound on its width according to an arithmetical spiral with a spread of 10 mm. The injection is made through the center, and the distance covered by the product is measured under the standard conditions of mold temperature (40C.). The injection is carried out at the maximum heat possible for the product, at the maximum possible injection speed and at the maximum injection pressure EXAMPLES 58 TO 61 These examples pertain to high temperature grafting polymerization. The parameters and proportions of reagents and results are given in Table 12.

The technique of polymerization employed is as follows:

In an autoclave equipped with a two-blade agitator inclined at 45, there is introduced water, a suspension agent, poly(vinyl alcohol) and the polyethylene is dispersed. After adding lauroyl peroxide and epoxidized soybean oil, the charge of vinyl chloride is then introduced. The reaction medium is brought to the desired temperature of polymerization, the partial pressure of the vinyl chloride reamining at all times lower than the saturated vapor pressure of the vinyl chloride at the selected temperature of polymerization. As soon as the reaction temperature is reached, the pressure drops and as soon as it is stabilized, the polymerization is stopped and the grafted product is collected. No crustobtained by means of polymerisation in suspension and having a K number measured in 1,2-dichloroethane equal to 66, in such an amount that the content of polyethylene in the mixture is equal to 7.5 percent by Proportion of grafting.

ing is observed on the walls of the reactor. weight and the content of grafted product is 15 percent The proportion of grafting (1') of the products which by weight. are obtained is determined by means of the extraction Example R62 given as a matter of comparison perof the non-grafted trunk in cyclohexane. The proportains to poly(vinyl chloride) not containing a grafted tion of grafting is then calculated in accordance with polymer. the usual formula, 1' (A-B/A) X 100, in which A is the After malaxation on a cylinder malaxor during a petotal weight of the polymer trunk in the sample and B riod of 5 minutes at 180C. in the presence of standard is the weight of the non-grafted polymer trunk. ingredients, a crepe is obtained which is cut into fine The proportions of grafting for each example are set strips; the apparent viscosity is determined at 180C. in forth in Table 12. The grafted polymer products are in a Gottfert and Wiedmann viscosimeter. the form of a powder, the granulometery of which is The results of these tests are set forth in Table 13 and below l,000 .t. clearly demonstrate that the grafted polymers obtained 7 i I W Table 12 Examples 58 59 60 61 Vinyl chloride 500 500 600 600 Polyethylene R 500 500 Reagents Polyethylene C 400 400 parts Water 2000 2000 2000 2000 Poly(vinyl weight alcohol) 4 4 4 4 Benzoyl peroxide 1 0.5 1.2 0.6 Epoxidizcd Soybean cpoxidc 2.5 2.5 3 3 'l'cmpcmturc, "(I 90 100 )0 I00 Volume of autoclave, liters 5 5 5 5 Conditions Agitation.

rev./minute 450 450 450 450 of Maximum partial pressure of vinyl chloride 17 20.5 1648 20.7 Polymerization kg/cm Saturated vapor pressure of vinyl chloride at the temperature of polymerization kgJcm. l8 21.4 18 21.4 Final pressure of polymerization =m. 6 7.5 6.4 7.7 Period of polymerization, h./min. 2.10 2 2 1.55 Yield, s0 85 88 85 Weight of vinyl chloride polymerized 610 600 730 720 Form of the product Powder Powder Powder Powder EXAMPLES 62 TO 66 The products obtained in accordance with Examples 58 to 61 are incorporated into a poly(vinyl chloride),

at a high temperature improve the fluidity of melted poly( vinyl chloride) which thereby facilitates the working of these compounds.

Table 13 Preparation of Grafted Polymers The results of the tests set forth in Table 13 demonstrate that the grafted polymers according to the present invention decrease the viscosity, in melted form, of the mixtures thereof with poly(vinyl chloride) It is normal for the voscosity of the composition obtained in accordance with Examples 65 and 66 to be lower than those of Examples 63 and 64, in view of the fact that the employment of polyethylene having a high fusion index for the production of grafted polymers decreases the viscosity, in melted form, of the mixtures of these polymers grafted with poly(vinyl chloride).

It should be pointed out, and this is one of the objects of the invention, that the application of high tempera- The shock resistance test called H50 is made on a series of samples of 100 bottles selected at random from the production. A first bottle, filled with water at 20C. and plugged, is allowed to fall from a height, estimated by an approximation method, on a flat anvil, free of water film. The bottles are guided by 6 fine nylon wires until the impact. The second bottle is allowed to fall 10 cm. above the preceding level if the first bottle has not withstood the drop, and so on. The average height which is necessary in order to have 50% of the bottles broken is then calculated. This value is set forth in Table 14.

Examples R67 and R68 are given for comparison.

Table 14 Examples R67 R68 69 70 Composition, g. Poly(vinyl chloride) K number 53 100 87 87 Poly (vinyl chloride) K number 60 87 Product of the present grafted polymer l3 l3 KUREHA BTA Ill l3 PARALOID K 120 N l Properties Resistance to shock height, m. 0.8 1.33 1.5 2.3 Rate of production bottles/hour 500 500 650 550 tures in the production of grafted polymers further decreases the viscosity, in melted form, of mixtures thereof with polymers of vinyl chloride and consequently, further facilitates the processing of these mixtures and makes it possible to work with them at lower temperatures which improves the thermal stability and the initial color of the finished products and also increases the productivity of the operations without any risk of deterioration of the polymer.

EXAMPLES 67 TO 70 These examples demonstrate high resistance to shock and the improved workability of compositions containing the grafted polymers according to the present invention in combination with low and high molecular weight poly(vinyl chloride).

It will be noted that resistance to shock of compositions containing the present grafted polymer is greater than that obtained by using well known reinforcing agents such as a grafted methacrylate polymer of methylmethacrylate-butadiene-styrene copolymer (KUREHA BTA III). The same holds true regarding the workability, the grafted polymers of the invention have proved to be superior to those of the well known processing-aid agents such as PARALOID K 120 N.

The grafted polymer employed has been obtained with the aid of polyethylene B and in accordance with the method described in Examples 49 and 50.

The characteristics of the poly(vinyl chlorides) which have been employed are set forth in Table 14. The stabilization of the resins is obtained by means of the addition of 1.5 parts of an octyltin mercaptide. The lubricant incorporated at the ratio of 1 part is an ester of montanic acid containing percent calcium montanate.

The bottles having a capacity of 1,000 cmfhave been obtained with the aid of a BEKUM HDB 1 10 type extruder. The very high rate of production of the bottles is clearly attributed to the presence of the grafted compounds according to the present invention.

What we claim as new and desire to secure by letters patent is:

1. Process for preparing grafted polymers of vinyl chloride in which vinyl chloride is polymerized or copolymerized in the presence of solid ethylene backbone polymer selected from the group consisting of polyethylene, a copolymer of ethylene with a minor quantity of another a-olefin and a combination thereof, said ethylene backbone polymer being present in an amount of about 25 to 99 percent by weight of the final grafted product, which comprises carrying out the polymerization in the presence of a polymer of ethylene having a fusion index 250, and having either the characteristic of from 0.2 to 4 double bonds per 1,000 carbon atoms or the characteristic from 5 to 30 methyl groups per 1,000 carbon atoms, or both of said characteristics at a temperature of about 40 to 110C, and under a partial pressure of vinyl chloride which is lower at all times than the saturated vapor pressure of vinyl chloride at the temperature of polymerization, the proportion of ethylene polymer to vinyl chloride being dependent on the capacityof said ethylene polymer for absorbing vinyl chloride and said proportion being such that substantially all of the vinyl chloride is absorbed by theethylene polymer, whereby substantially all of said vinyl chloride is polymerized in direct contact with said ethylene polymer.

2. Process for obtaining grafted polymers of vinyl chloride in accordance with claim 1 in which the fusion index of the polymer of ethylene is between 0.1 and 0.3.

3. Process for obtaining grafted polymers of vinyl chloride in accordance with claim 1 in which the fusion index of the polymer of ethylene is between 0.3 and 40.

4. Process for obtaining grafted polymers of vinyl chloride in accordance with claim 1 in which the fusion index of the polymer of ethylene is between 40 and 200.

5. Process for obtaining grafted polymers of vinyl chloride in accordance with claim 1 in which the polymerization is carried out at a temperature of to C.

V a liquid phase.

9. Process in accordance with claim 1 in which the polymerization is carried out in the presence of a stabilizer of poly(vinyl chloride).

10. Process in accordance with claim 1 in which the polymerization is carried out in an aqueous suspension in the presence of a suspension agent.

11. A process in accordance with claim 1 in which siad polymerization is carried out in aqueous suspension. 

2. Process for obtaining grafted polymers of vinyl chloride in accordance with claim 1 in which the fusion index of the polymer of ethylene is between 0.1 and 0.3.
 3. Process for obtaining grafted polymers of vinyl chloride in accordance with claim 1 in which the fusion index of the polymer of ethylene is between 0.3 and
 40. 4. Process for obtaining grafted polymers of vinyl chloride in accordance with claim 1 in which the fusion index of the polymer of ethylene is between 40 and
 200. 5. Process for obtaining grafted polymers of vinyl chloride in accordance with claim 1 in which the polymerization is carried out at a temperature of 80* to 110*C.
 6. Process in accordance with claim 1 in which the backbone polymer is in the form of granules, powder, fluff, fibers, plates or films.
 7. Process in accordance with claim 1 in which additional vinyl chloride is introduced during the course of the polymerization reaction either in a continuous manner or in successive portions.
 8. Process in accordance with claim 1 in which the polymerization is carried out in bulk, in the absence of a liquid phase.
 9. Process in accordance with claim 1 in which the polymerization is carried out in the presence of a stabilizer of poly(vinyl chloride).
 10. Process in accordance with claim 1 in which the polymerization is carried out in an aqueous suspension in the presence of a suspension agent.
 11. A process in accordance with claim 1 in which siad polymerization is carried out in aqueous suspension. 